Most viscous materials such as lotions, dentifrices, glues, caulks and other products are stored in and dispensed from single chamber tubular containers. Since only one substance is being dispensed, there is no problem concerning the uniformity of the dispensing. In addition, there is no problem with regard to the suckback of air into the tubular container to replace the product that has been dispensed. However, the uniformity of dispensing is a problem with regard to multichamber-chamber tubular containers. In most instances, it is desired to dispense these products in a particular uniform ratio. This can be in equal amounts or in essentially any ratio of one to the other. The objective is to have this uniform dispensing from the first dispensing through to the last dispensing, regardless of how the tubular container is pressurized and the product is dispensed. Further, after the products are dispensed, there preferably should not be a suckback of air down into the tubular container to replace the products that have been dispensed. There can be some suckback of the products from the tip of the dispensing nozzle further down into the nozzle. However, the suckback should not draw air clown into the chambers of the tubular container.
If air is drawn down into the chambers of the tubular container, bubbles of varied number and sizes will be formed within the chambers. Then, during subsequent dispensing product alone may be dispensed from one or more chambers and air and product from one or more other chambers. The net result will be a non-uniform dispensing of the components.
It also is important that the tubular container have a structure whereby the position of the application of the dispensing force will not materially affect the uniformity of the dispensing. That is, whether the dispensing force is parallel or perpendicular to a tubular container chamber dividing wall, the amount of each product dispensed will be uniform. Likewise, the amount of each product dispensed should be uniform regardless of whether the tubular container is squeezed using two, three or four fingers or the full hand.
There is considerable prior art in the area of multichamber tubular containers. These generally are of two different categories. A first category consists of tubular containers where one chamber is surrounded by another chamber. These are sometimes called "tube in a tube" containers. It is difficult to uniformly dispense products form this type of tubular container. This is the case since the dispensing pressure is applied to only one chamber and there are narrow channels for dispensing each product. A second category consists of side by side chambers. This is a type that is more amenable to uniform dispensing and the present invention is directed to this type of tubular container. The present invention is directed to characteristics of this type of tubular container for the uniform dispensing of products of related rheologies.
The general prior art is exemplified by a tube-in-a-tube structure as illustrated in U.S. Pat. No. 4,211,341 which discloses a tubular container having two concentric chambers where there is a large amount of one substance and a lesser amount of another substance. U.S. Pat. No. 2,939,610 and U.S. Pat. No. 2,959,327 disclose other structures for a tube-in-a-tube type of multichamber container. A side-by-side type of arrangement of a multichamber tubular container is shown in U.S. Pat. Nos. 1,894,115; 2,944,705; 4,089,437 and 5,244,120. Each of these patents discloses a tubular container where two substances are separately stored. They come into contact only after dispensing. Each of these patents discloses a structure of an outer wall and an inner web. In addition, in U.S. Pat. No. 4,089,437, there is disclosed the use of a pressure responsive moveable septum as a part of the web. This consists of a part of the divider web adjacent the dispensing end of the tubular container having a corrugated or bulbous structure. The objective is to have this septum readily flex to distribute the applied dispensing forces to the outer wall equally to the substances in each chamber.
The problem of uniform dispensing of substances from multichamber tubular containers is recognized in U.S. Pat. No. 4,089,437. The objective is to have uniform dispensing of contained substances regardless of how the tubular container is squeezed during a dispensing. However, this problem is not effectively solved in U.S. Pat. No. 4,089,437.
The objective is that regardless of whether the tubular container is squeezed from the bottom or the top, or parallel or perpendicular to the divider web, there should be a uniform dispensing of the container substances. In addition, the dispensing should be uniform from the first dose to the last dose. This is not effectively accomplished in U.S. Pat. No. 4,089,437. The use of a pressure responsive septum does not solve the problem.